Chinese cork oak
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Chinese cork oak ( Quercus variabilis ) |
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The Chinese cork oak ( Quercus variabilis ) is a deciduous tree belonging to the oak genus . It is an important medium-sized forest tree in southeast China, but little known in Europe. It deserves the name Chinese cork oak because of the thick layers of cork that it forms, similar to the cork oak . The cork is harvested at regular intervals. The leaves, which are similar to those of chestnuts , and the almost round acorns, two thirds of which are covered by the fruit cups , are striking .
description
The Chinese cork oak is a deciduous tree that grows up to a maximum height of 45 meters and a trunk diameter ( BHD ) of 1 meter. The average height is 18 meters with trunk diameters between 20 and 33 centimeters. The crown is broad and rounded and is formed by strong branches.
The deeply furrowed bark is gray-brown to blackish and is 2 to 5 centimeters thick. Older trees form a dark brown cork layer that is used economically. The wood has a yellow-brown sapwood and a reddish-brown core . It is ring-pored and straight-grained. The Chinese cork oak forms a strong, deep tap root system that can reach a depth of 1 meter after a year. The roots of older trees protrude to a depth of 6 to 7 meters. The side roots are 6 to 7 meters long and grow particularly dense in the upper soil layers.
The winter buds are yellowish brown and are 3 to 5 millimeters long. The leaves are alternate and 8 to 20 centimeters long and 2 to 5 centimeters wide. They are not lobed, have an elongated elliptical shape and a somewhat notched edge. They thus resemble the leaves of chestnuts . 9 to 18 pairs of leaf veins are formed, which end in short bristles protruding over the edge of the leaf. The leaf stalks are 1 to 5 inches long and glabrous. The upper side of the leaf is dark green, the dense star hairs make the underside of the leaf appear gray-white.
The Chinese cork oak is single sexed. The male flowers grow in 14 centimeter long catkins that are covered with short yellow-brown hair. They have five stamens , the inflorescence is five- to six-lobed and leathery. The female flowers stand individually in the leaf axils and also form a five to six-part flower envelope and three styles . Rarely do you see regressed stamens.
The acorns are broadly egg-shaped, and have a diameter of 2.5 to 4 centimeters and are 1.5 to a maximum of 2.7 centimeters long. Two thirds of them are enclosed in the fruit cup . The fruit cup is covered by numerous, upwardly rolled, overlapping and tapering scales.
The Chinese oak blooms from March to April, the acorns ripen in October and September.
The number of chromosomes is 2n = 24.
Distribution and location requirements
The Chinese cork oak thrives in the hills and mountains of warm, temperate and subtropical zones in southeastern China. The center of the range is West Hubei , the Qin Ling Mountains and the Dabie Shan Mountains. They are also found in Korea, Japan, and Taiwan. It grows at altitudes between 10 and almost 2500 meters. The annual mean temperatures in the natural range are between 12 and 16 ° C, cold down to −18 ° C is tolerated. The annual amount of precipitation ranges from 500 to 1,600 millimeters. It needs a lot of light and is sensitive to shading. The cork layer and the deep root system make it insensitive to drought, storms and drought. The species grows on both acidic and slightly alkaline soils with pH values of 4 to 8. Nutrient-rich and well-drained soils made of loam or sandy loam are particularly beneficial .
ecology
The Chinese cork oak enters into a mycorrhizal symbiosis with the chanterelle ( Cantharellus cibarius ) .
The acorns are attacked by the weevil Curculio davidi , young plants are damaged by several rodents, such as the Père David red squirrel ( Sciurotamias davidianus ) from the genus of the Chinese red squirrel and the long-tailed dwarf hamster ( Cricetulus longicaudatus ) from the genus of the gray hamster . The cork may be caused by the fungus Truncopora truncatospora be attacked, the sheets through the rust fungus Cronartium quercuum , the wood by the wood rot causing Lackporlingen Ganoderma lobatum and Ganoderma lucidum .
Systematics
The Chinese cork oak belongs to the section of oak trees in the oak genus. It can be crossed with the cork oak , the resulting offspring are harder to frost than both parents ( heterosis ).
use
The most important economic use is the extraction of the cork. It has a low density of 150 to 300 kg / m 3 and is highly elastic, water-repellent, withstands acids and bases , is sound-absorbing and corrosion-resistant. The cork is processed into insulating mats that are used in the electrical industry, in mechanical engineering and for packaging. Trees with a trunk diameter of 13 to 15 centimeters, which can be reached from an age of 15 to 20 years, are suitable for cork use. Cork can be harvested about every 10 years when the cork layer has reached a thickness of 1.5 to 2 centimeters.
The acorns are used as a nutritious fodder because of their high carbohydrate content. The wood is used as construction timber, but also in shipbuilding and in carpentry.
proof
literature
- Schütt, Weisgerber, Schuck, Lang, Stimm, Roloff: Encyclopedia of Deciduous Trees . Nikol, Hamburg 2006, ISBN 3-937872-39-6 , pp. 507-512 .
Individual evidence
- ↑ a b Schütt et al .: Encyclopedia of Deciduous Trees . P. 508
- ↑ a b c d e f g Schütt et al .: Encyclopedia of Deciduous Trees . P. 510
- ↑ Quercus variabilis at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ a b c Schütt et al .: Encyclopedia of Deciduous Trees . P. 511
- ↑ Schütt et al .: Encyclopedia of Deciduous Trees . P. 512
Web links
- Quercus variabilis. In: Flora of China Vol. 4. www.eFloras.org, p. 372 , accessed on June 19, 2009 (English).